It seems like it might be difficult to test really complex CSS like drop-down menus, interactive hover effects, etc Such complex CSS behaviors are probably bet

It seems like it might be difficult to test really complex CSS like drop-down menus, interactive hover effects, etc Such complex CSS behaviors are probably better off being tested by an integration test. It would be so great to have unit testing to keep an eye on these kinds of things. Agreed! The Cactus approach does work well for unit tests.